The influence of training on decision times and errors associated with classifying trunk postures using video-based posture assessment methods

Abstract

The purpose of this study was to examine the influence of training on the decision times and errors associated with video-based trunk posture classifications. Altogether, 30 amateur and 30 knowledge-based participants completed a three-phase study (pre-training, training, post-training) that required them to classify static trunk postures in images on a computer screen into a posture category that represented the angle of the trunk depicted. Trunk postures were presented in both flexion/extension and lateral bend views and at several distances from the boundaries of the posture categories. Both decision time and errors decreased as distance from the boundaries increased. On average, amateur analysts experienced a larger decrease in decision time per posture classification than knowledge-based analysts (amateur: 0.79 s, knowledge-based: 0.60 s; p <0.05) suggesting that training can have beneficial effects on classification performance. The implications are that the analysis time associated with video-based posture assessment methods can be reduced with appropriate training, making this type of approach feasible for larger-scale field studies. Statement of Relevance:Understanding the role that training can play in reducing errors associated with the use of video-based posture assessment methods may result in more efficient use of these tools by ergonomic practitioners. Reducing decision time and misclassification errors will provide a more efficient, accurate and representative assessment of injury risk.

Cost-efficient assessment of biomechanical exposure in occupational groups, exemplified by posture observation and inclinometry

“…This might be in the form of resampling existing direct measurements (1, 12, 13), or repeated observation of video film to investigate inter-rater differences or compare different processing schemes (21,32). Scenario 3 describes a situation where no new data collection is required, resulting in a substantial reduction in total study cost.…”

“…Observation has long been believed to represent a middle ground in that they are more objective than self-reports (19,27,29), yet less consistent than direct measurements. The suspected inferior precision associated with using observational methods would mainly be a result of variability introduced by within-and betweenobserver differences in opinions when viewing the same posture (21,(32)(33)(34). At the same time, observations have been anecdotally claimed to be cheaper in use than direct measurements (27).…”

Observation-based posture assessment: review of current practice and recommendations for improvement.

“…In both cases, active involvement on the part of the inspector/analyst during training was critical to success. Inexperienced analysts appear to benefit more from training than experienced analysts [Weir et al 2011], but there is error inherent in all perceptual tasks. However, regardless of experience, all analysts can make improvements in their performance with practice [Andrews et al 2008b].…”

“…Training has been shown to improve the reliability of industrial inspection performance and to decrease the decision time of analysts coding postures [Weir et al 2011]. In both cases, active involvement on the part of the inspector/analyst during training was critical to success.…”

“…One reason for this is that postures have not been standardized across the methods in the size, and therefore number, of posture categories used to quantify working posture [Andrews et al 2008a[Andrews et al , 2008bKeyserling 1986;Juul-Kristensen et al 2001;Lowe 2004a;Weir et al 2011]. One reason for the lack of consistency between studies is the nature of the job or task and that the characteristics of the physical exposures in the job affect the decision about type of assessment, sampling approach, and summary measures to be adopted.…”